Semiconductor manufacturing apparatus and method for cleaning same

ABSTRACT

An LPCVD apparatus is provided with a processing chamber and a reaction cooling apparatus. The reaction cooling apparatus is placed outside the processing chamber and is configured to generate hydrogen fluoride gas by reaction of hydrogen gas and fluorine gas and to cool the hydrogen fluoride gas. The hydrogen fluoride gas cooled by the reaction cooling apparatus is supplied into the processing chamber as a cleaning gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2008-250259, filed on Sep. 29,2008; the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a semiconductor manufacturing apparatus and amethod for cleaning the same using a cleaning gas generated by thereaction of a combustible gas and a combustion-supporting gas.

2. Background Art

In an LPCVD (low pressure chemical vapor deposition) apparatus, in thecourse of its use, a deposition film of thin film materials isinevitably formed inside its processing chamber. The thin film materialsinclude, for instance, silicon, silicon oxide, or silicon nitride to bedeposited on a silicon wafer. Such a deposition film, when thickened, isdelaminated into particles, which unfortunately contaminate the insideof the processing chamber and the wafer.

Thus, the inside of the processing chamber needs to be regularly cleanedto remove the deposition film. As a method for this cleaning, atechnique of etching the deposition film by a cleaning gas containinghydrogen fluoride gas (HF) is developed. However, while the supply pipeof the cleaning gas is typically formed from stainless steel, hydrogenfluoride gas (HF) has very high corrosivity. Hence, if hydrogen fluoridegas itself is introduced into the processing chamber, it corrodes thesupply pipe. Then, metal fluorides generated by corrosion flow into theprocessing chamber and contaminate the inside of the processing chamberand the wafer. Thus, an alternative cleaning technique is proposed in,e.g., JP-A-2008-098431(Kokai). In this technique, fluorine gas (F₂) andhydrogen gas (H₂) are separately introduced into the processing chamberand reacted therein to generate hydrogen fluoride gas (HF), which isused to clean the processing chamber.

However, the inventors have discovered that the inside of the processingchamber is locally damaged when it is cleaned by the method described inJP-A-2008-098431(Kokai).

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided asemiconductor manufacturing apparatus including: a processing chamber;and a reaction cooling apparatus placed outside the processing chamberand configured to generate a cleaning gas by reaction of a combustiblegas and a combustion-supporting gas and to cool the cleaning gas, thecleaning gas which is cooled being supplied into the processing chamber.

According to another aspect of the invention, there is provided asemiconductor manufacturing apparatus including: a processing chamber; acombustible gas supply pipe configured to supply a combustible gas intothe processing chamber; a combustion-supporting gas supply pipeconfigured to supply a combustion-supporting gas into the processingchamber; and at least one of another combustible gas supply pipe andanother combustion-supporting gas supply pipe, one of the combustiblegas supply pipe and the another combustible gas supply pipe for passingthe combustible gas is temporally changed among them or one of thecombustion-supporting gas supply pipe and the anothercombustion-supporting gas supply pipe for passing thecombustion-supporting gas is temporally changed among them.

According to still another aspect of the invention, there is provided amethod for cleaning a semiconductor manufacturing apparatus, including:a first supplying a combustible gas and a combustion-supporting gas intoa processing chamber; and a second supplying the combustion-supportinggas into the processing chamber, the first supplying and the secondsupplying being alternately performed.

According to still another aspect of the invention, there is provided amethod for cleaning a semiconductor manufacturing apparatus, including:supplying a combustible gas and a dilution gas into a processing chamberthrough a combustible gas supply pipe, and simultaneously supplying acombustion-supporting gas and a dilution gas into the processing chamberthrough a combustion-supporting gas supply pipe, at least one of a firstsupply amount of the dilution gas supplied through the combustible gassupply pipe and a second supply amount of the dilution gas suppliedthrough the combustion-supporting gas supply pipe being temporallychanged.

According to still another aspect of the invention, there is provided amethod for cleaning a semiconductor manufacturing apparatus including aprocessing chamber, a combustible gas supply pipe configured to supply acombustible gas into the processing chamber, and a combustion-supportinggas supply pipe configured to supply a combustion-supporting gas intothe processing chamber, at least one of the combustible gas supply pipeand the combustion-supporting gas supply pipe being provided in aplurality, the method including: temporally changing the supply pipe forpassing the combustible gas or the combustion-supporting gas among theplurality of combustible gas supply pipes or the plurality ofcombustion-supporting gas supply pipes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a semiconductor manufacturingapparatus according to a first embodiment of the invention;

FIG. 2 is a cross-sectional view illustrating the reaction coolingapparatus shown in FIG. 1;

FIG. 3 is a schematic view illustrating a semiconductor manufacturingapparatus according to a comparative example of the first embodiment;

FIG. 4 is a schematic view illustrating a semiconductor manufacturingapparatus according to a second embodiment of the invention;

FIG. 5 is a perspective view illustrating the triple pipe shown in FIG.4;

FIG. 6 is a perspective view illustrating a triple pipe in a variationof the second embodiment;

FIG. 7 is a schematic view illustrating a semiconductor manufacturingapparatus according to a third embodiment of the invention;

FIG. 8 is a graph illustrating change in the supply amount of each gasin the third embodiment, where the horizontal axis represents time, andthe vertical axis represents gas supply amount;

FIG. 9 is a graph illustrating change in the supply amount of each gasin a fourth embodiment of the invention, where the horizontal axisrepresents time, and the vertical axis represents gas supply amount;

FIG. 10 is a graph illustrating change in the supply amount of each gasin a first variation of the fourth embodiment, where the horizontal axisrepresents time, and the vertical axis represents gas supply amount;

FIG. 11 is a graph illustrating change in the supply amount of each gasin a second variation of the fourth embodiment, where the horizontalaxis represents time, and the vertical axis represents gas supplyamount;

FIG. 12 is a plan view illustrating a semiconductor manufacturingapparatus according to a fifth embodiment of the invention; and

FIG. 13 is a graph illustrating a cleaning method according to the fifthembodiment, where the horizontal axis represents time, and the verticalaxis represents gas supply amount.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention will now be described with reference to thedrawings.

At the outset, a first embodiment of the invention is described.

FIG. 1 is a schematic view illustrating a semiconductor manufacturingapparatus according to this embodiment.

FIG. 2 is a cross-sectional view illustrating the reaction coolingapparatus shown in FIG. 1.

The semiconductor manufacturing apparatus according to this embodimentis an apparatus for manufacturing a semiconductor device, such as an LSI(large-scale integrated circuit) chip, and more specifically an LPCVDapparatus.

As shown in FIG. 1, the LPCVD apparatus 1 according to this embodimentincludes a processing chamber 11 for forming a thin film on a workpiece,such as a silicon wafer, by the LPCVD method. In the processing chamber11 is provided a wafer boat 12 or other jig for holding workpieces (notshown), such as silicon wafers. The processing chamber 11 and the waferboat 12 or other jig are formed from quartz.

In the LPCVD apparatus 1, in the course of its use, a deposition film isformed inside the processing chamber 11, that is, on the surface of theinner wall of the processing chamber 11 and the wafer boat 12 or otherjig. Thus, in this embodiment, hydrogen fluoride gas (HF) is used as acleaning gas to remove this deposition film. Hydrogen fluoride gas (HF)is generated by the combustion reaction of hydrogen gas (H₂) andfluorine gas (F₂). In this specification, the combustion reaction refersto an exothermic chemical reaction, caused by coupling between at leastone combustible gas and at least one combustion-supporting gas. Thecombustion-supporting gas is not limited to oxygen. For instance, it isfluorine in this embodiment.

A reaction chamber 13 is provided outside the processing chamber 11. Thereaction chamber 13 is in connection with the processing chamber 11 byan HF supply pipe 14. The reaction chamber 13 and the HF supply pipe 14are illustratively formed from alumina (Al₂O₃). The HF supply pipe 14 isprovided with a valve 14 a.

The reaction chamber 13 is in connection with a hydrogen gas supply pipe15 and a fluorine gas supply pipe 16. The hydrogen gas supply pipe 15and the fluorine gas supply pipe 16 serve to supply hydrogen gas (H₂)and fluorine gas (F₂), respectively, into the reaction chamber 13, andare illustratively formed from stainless steel. The hydrogen gas supplypipe 15 and the fluorine gas supply pipe 16 are provided with valves 15a and 16 a, respectively.

The processing chamber 11 is also in connection with another fluorinegas supply pipe 17. The fluorine gas supply pipe 17 serves to directlysupply fluorine gas (F₂) into the processing chamber 11 without theintermediary of the reaction chamber 13, and is illustratively formedfrom stainless steel. The fluorine gas supply pipe 17 is provided with avalve 17 a. Furthermore, a vacuum pump 18 is provided outside theprocessing chamber 11. The processing chamber 11 is in connection withthe vacuum pump 18 by an exhaust pipe 19.

As shown in FIGS. 1 and 2, a water-cooling apparatus 21 as a coolingmechanism is provided around the reaction chamber 13. The water-coolingapparatus 21 is a hollow structure illustratively made of a metal, andits outer wall is in contact with the outer wall of the reaction chamber13. The water-cooling apparatus 21 cools the reaction chamber 13 byallowing cooling water to flow through this hollow structure.

A jacket heater 22 as a heating mechanism is wound around the outersurface of the HF supply pipe 14. The jacket heater 22 is an electricheater in which an electric heating wire is provided in a sheet-likeheat insulator. The jacket heater 22 produces heat upon energization andheats the HF supply pipe 14. Furthermore, a temperature sensor 23, suchas a thermocouple, is attached to the outer surface of the HF supplypipe 14. The reaction chamber 13, the HF supply pipe 14, thewater-cooling apparatus 21, the jacket heater 22, and the temperaturesensor 23 constitute a reaction cooling apparatus 25.

Next, a description is given of the operation of the semiconductormanufacturing apparatus according to this embodiment configured asdescribed above, that is, a method for cleaning a semiconductormanufacturing apparatus according to this embodiment.

The valves 14 a, 15 a, and 16 a are opened. While the vacuum pump 18 isactivated to evacuate the processing chamber 11, hydrogen gas (H₂) issupplied to the hydrogen gas supply pipe 15 at a flow rate of e.g. 1 slm(standard liter/min), and fluorine gas (F₂) is supplied to the fluorinegas supply pipe 16 at a flow rate of e.g. 1 slm. On the other hand,fluorine gas (F₂) is supplied into the processing chamber 11 through thefluorine gas supply pipe 17. Furthermore, the water-cooling apparatus 21is activated to pass cooling water through the water-cooling apparatus21. Moreover, the temperature sensor 23 is activated.

Thus, hydrogen gas and fluorine gas are supplied into the reactionchamber 13. Hydrogen gas is a combustible gas, and fluorine gas is acombustion-supporting gas. Hence, these gases react to generate hydrogenfluoride gas (HF), which serves as a cleaning gas. At this time, heat ofreaction is produced by the reaction of hydrogen gas and fluorine gas.This heat of reaction is transferred through the reaction chamber 13 tothe water-cooling apparatus 21 and exhausted by the cooling waterflowing in the water-cooling apparatus 21. That is, the water-coolingapparatus 21 cools the cleaning gas through the reaction chamber 13.

Then, the cooled cleaning gas is introduced through the HF supply pipe14 into the processing chamber 11. The hydrogen fluoride gas (HF)introduced from the HF supply pipe 14 into the processing chamber 11 ismixed with the fluorine gas (F₂) introduced through the fluorine gassupply pipe 17 into the processing chamber 11. This mixed gas etches thesurface of the inner wall of the processing chamber 11 and the waferboat 12 or other jig and removes the deposition film. Thus, the insideof the processing chamber 11 is cleaned.

Here, hydrogen gas and fluorine gas react in the reaction chamber 13placed outside the processing chamber 11 and are turned into hydrogenfluoride gas, which is sufficiently cooled by the water-coolingapparatus 21 and then introduced into the processing chamber 11. Hence,there is no case where hydrogen gas and fluorine gas react in theprocessing chamber 11 to locally reach a high temperature, causingdamage to the processing chamber 11 and the wafer boat 12 or other jig.

Furthermore, the temperature of the cleaning gas flowing through the HFsupply pipe 14 is measured by the temperature sensor 23. When thetemperature of the cleaning gas is excessively decreased, the jacketheater 22 is activated to heat the cleaning gas. Thus, the temperatureof the cleaning gas is kept at a constant temperature, such as 50° C.This allows etching under a constant condition.

Next, the effect of this embodiment is described.

As described above, according to this embodiment, hydrogen gas andfluorine gas are reacted in the reaction chamber 13 placed outside theprocessing chamber 11 to generate hydrogen fluoride gas, which issufficiently cooled by the water-cooling apparatus 21 and thenintroduced into the processing chamber 11. Hence, there is no case wherehydrogen gas and fluorine gas react in the processing chamber 11 toproduce a high-temperature flame, the heat of which causes damage to theprocessing chamber 11, the wafer boat 12 and the like. That is, damagedue to cleaning can be prevented.

Furthermore, the reaction chamber 13 and the HF supply pipe 14 aresuperior in heat resistance and thermal conductivity because they areformed from alumina. Thus, they are not damaged by hydrogen fluoride gasand the heat of reaction, and can efficiently cool the cleaning gas.Here, the material of the reaction chamber 13 and the HF supply pipe 14is not limited to alumina, but can be any material superior in heatresistance and thermal conductivity.

Furthermore, the cooling mechanism for cooling the cleaning gas isimplemented by the water-cooling apparatus 21. Thus, this embodiment canrealize a cost-effective cooling mechanism with easy procurement andmaintenance and high cooling efficiency.

Furthermore, hydrogen gas and fluorine gas are separately introducedinto the reaction chamber 13. Hence, even if the hydrogen gas supplypipe 15 and the fluorine gas supply pipe 16 are formed from stainlesssteel, these supply pipes are not corroded by hydrogen fluoride gas.Thus, general-purpose stainless steel pipes can be used for the hydrogengas supply pipe 15 and the fluorine gas supply pipe 16.

Furthermore, the jacket heater 22 is provided in this embodiment. Hence,the temperature of the cleaning gas is not excessively decreased, andthe deposition film can be etched under a suitable condition.Furthermore, because the temperature sensor 23 is provided, thetemperature of the cleaning gas can be accurately monitored.

Here, even without the jacket heater 22, the cleaning gas is heated bythe reaction of hydrogen gas and fluorine gas, and cooled by thewater-cooling apparatus 21. Hence, by adjusting the balance betweenthese heating and cooling, the temperature of the cleaning gas can bekept constant. Furthermore, even without the temperature sensor 23, thetemperature of the cleaning gas can be monitored by, for instance, atemperature sensor (not shown) provided in the processing chamber 11.However, by providing the jacket heater 22 and the temperature sensor23, the temperature of the cleaning gas can be controlled more easilyand accurately.

Next, a comparative example of this embodiment is described.

FIG. 3 is a schematic view illustrating a semiconductor manufacturingapparatus according to this comparative example.

As shown in FIG. 3, in contrast to the LPCVD apparatus 1 (see FIG. 1)according to the above first embodiment, the LPCVD apparatus 101according to this comparative example does not include the reactioncooling apparatus 25, but hydrogen gas (H₂) and fluorine gas (F₂) aredirectly supplied into the processing chamber 11 through a hydrogensupply pipe 102 and a fluorine supply pipe 103, respectively. Thus,hydrogen gas and fluorine gas react inside the processing chamber 11 togenerate hydrogen fluoride gas (HF). A mixed gas of this hydrogenfluoride gas (HF) and fluorine gas (F₂) is used to etch the depositionfilm. In FIG. 3, for clarity of illustration, the wafer boat 12 (seeFIG. 1) is not shown.

In this comparative example, hydrogen gas and fluorine gas are mixed inthe processing chamber 11. Hydrogen reacts violently with fluorine toproduce heat of reaction, hence locally producing a high-temperatureflame. This flame is produced always in the same region 112, because itis produced at the position where hydrogen gas and fluorine gasintroduced into the processing chamber 11 meet with each other. Hence,in this region 112, the processing chamber 11 and the wafer boat orother jig made of quartz are damaged by the heat of reaction, causinglocal damage 113. This requires frequent replacement of components.Furthermore, dust occurs from the damaged portion. This results indecreasing the productivity of semiconductor devices.

In contrast, the above first embodiment can prevent damage to theprocessing chamber and the like due to cleaning, achieving low frequencyof replacing components and little dust generation. Thus, semiconductordevices can be manufactured with high productivity.

Next, a second embodiment of the invention is described.

FIG. 4 is a schematic view illustrating a semiconductor manufacturingapparatus according to this embodiment.

FIG. 5 is a perspective view illustrating the triple pipe shown in FIG.4.

The semiconductor manufacturing apparatus according to this embodimentis also an LPCVD apparatus.

As shown in FIG. 4, in contrast to the LPCVD apparatus 1 (see FIGS. 1and 2) according to the above first embodiment, the LPCVD apparatus 2according to this embodiment includes a triple pipe 31 as a reactioncooling apparatus instead of the reaction cooling apparatus 25. The endportion of the triple pipe 31 is coupled to the processing chamber 11.

As shown in FIGS. 4 and 5, the triple pipe 31 includes an outer tube 32,a middle tube 33, and an inner tube 34 coaxially in this order fromoutside. That is, the middle tube 33 is placed inside the outer tube 32,and the inner tube 34 is placed inside the middle tube 33. The outertube 32, the middle tube 33, and the inner tube 34 are illustrativelyformed from alumina.

The end portion of the outer tube 32 is coupled to the processingchamber 11, and the inside of the outer tube 32 is in connection withthe inside of the processing chamber 11. The middle tube 33 isterminated at a position spaced from the processing chamber 11, and theterminated portion is opened to inside the outer tube 32. Furthermore,the inner tube 34 is also terminated at a position spaced from theprocessing chamber 11, and the terminated portion is opened to insidethe outer tube 32. For instance, the middle tube 33 and the inner tube34 are terminated at the same position. Thus, the middle tube 33 and theinner tube 34 are not placed inside the portion of the outer tube 32 onthe processing chamber 11 side, and this portion constitutes a singlecontinuous space 35.

Hydrogen gas (H₂) is supplied into the inner tube 34. Fluorine gas (F₂)is supplied between the inner tube 34 and the middle tube 33.Furthermore, a cooling gas is supplied between the middle tube 33 andthe outer tube 32. The cooling gas is a gas which does not react withthe combustible gas and the combustion-supporting gas. In thisembodiment, the cooling gas is a gas which does not react with hydrogengas (H₂) and fluorine gas (F₂), such as nitrogen gas (N₂). Thetemperature of the cooling gas is preferably room temperature or less.That is, the cooling gas can be at room temperature, or can be cooled toa temperature lower than room temperature, but preferably, it is notheated at least actively. The configuration of this embodiment otherthan the foregoing is the same as that of the above first embodiment.

Next, the operation and effect of this embodiment are described.

A combustible gas, a combustion-supporting gas, and a cooling gas aresupplied to the triple pipe 31 from its portion not communicating withthe processing chamber 11. Here, hydrogen gas (H₂), which is acombustible gas, is supplied into the inner tube 34, fluorine gas (F₂),which is a combustion-supporting gas, is supplied between the inner tube34 and the middle tube 33, and nitrogen gas (N₂), which is a coolinggas, is supplied between the middle tube 33 and the outer tube 32. Thesegases flow separately in the portion of the triple pipe 31 where themiddle tube 33 and the inner tube 34 are placed, but mixed with eachother in the space 35. Thus, hydrogen gas and fluorine gas react togenerate hydrogen fluoride gas (HF). At this time, heat of reaction isproduced, but cooled by the nitrogen gas having a temperature of roomtemperature or less. After the reaction is substantially completed, thehydrogen fluoride gas is introduced into the processing chamber 11 inthe sufficiently cooled state.

Also in this embodiment, like the above first embodiment, hydrogen gasand fluorine gas react outside the processing chamber 11 to generatehydrogen fluoride gas, which is cooled and then introduced into theprocessing chamber 11. Hence, damage to the processing chamber 11 andthe like due to heat of reaction can be prevented. Furthermore, even ifunreacted hydrogen gas and fluorine gas are introduced into theprocessing chamber 11, these gases have been diluted by nitrogen gas.Hence, the reaction can be suppressed, and damage to the processingchamber 11 and the like can be prevented. The operation and effect ofthis embodiment other than the foregoing are the same as those of theabove first embodiment.

In this embodiment, the triple pipe 31 is supplied with hydrogen gas,fluorine gas, and nitrogen gas in this order from inside. However, theinvention is not limited thereto, but they are supplied in the order of,for instance, fluorine gas, hydrogen gas, and nitrogen gas from inside.Furthermore, the cooling gas is not limited to nitrogen gas, but can beany gas which does not react with hydrogen gas and fluorine gas. Here,if the cooling gas is a gas with large specific heat, such as carbondioxide (CO₂), then the cooling efficiency can be increased.Furthermore, the material of the triple pipe 31 is not limited toalumina, but can be any material superior in heat resistance and thermalconductivity.

Next, a variation of this embodiment is described.

FIG. 6 is a perspective view illustrating a triple pipe in thisvariation.

As shown in FIG. 6, in this variation, a water-cooling apparatus 36, ajacket heater 37, and a temperature sensor 38 are attached to the outersurface of the triple pipe 31. The operation of the water-coolingapparatus 36, the jacket heater 37, and the temperature sensor 38 is asdescribed in the above first embodiment. Thus, according to thisvariation, the temperature of the cleaning gas can be controlled moreeasily and accurately. The configuration, operation, and effect of thisvariation other than the foregoing are the same as those of the abovesecond embodiment.

Next, a third embodiment of the invention is described.

FIG. 7 is a schematic view illustrating a semiconductor manufacturingapparatus of this embodiment.

FIG. 8 is a graph illustrating change in the supply amount of each gasin this embodiment, where the horizontal axis represents time, and thevertical axis represents gas supply amount.

In this specification, the “supply amount” refers to the amount of gasintroduced into the processing chamber 11 per unit time.

As shown in FIG. 7, in contrast to the LPCVD apparatus 1 (see FIG. 1)according to the above first embodiment, the LPCVD apparatus 3 used inthis embodiment does not include the reaction cooling apparatus 25. Ahydrogen/nitrogen supply pipe 41 and a fluorine/nitrogen supply pipe 42are in direct connection with the processing chamber 11. Theconfiguration of the LPCVD apparatus 3 other than the foregoing is thesame as that of LPCVD apparatus 1 according to the above firstembodiment.

Next, a method for cleaning a semiconductor manufacturing apparatusaccording to this embodiment is described.

As shown in FIG. 7, according to this embodiment, in the LPCVD apparatus3, a mixed gas (hereinafter referred to as “H₂/N₂ gas”) of hydrogen gas(H₂) and nitrogen gas (N₂) is introduced into the processing chamber 11through the hydrogen/nitrogen supply pipe 41, and a mixed gas(hereinafter referred to as “F₂/N₂ gas”) of fluorine gas (F₂) andnitrogen gas (N₂) is introduced into the processing chamber 11 throughthe fluorine/nitrogen supply pipe 42. The temperature of each gas isillustratively room temperature. Each gas is mixed not immediatelybefore being introduced into the processing chamber 11 but at a positionremotely distanced from the processing chamber 11. For instance,hydrogen gas and fluorine gas are mixed with nitrogen gas at a positionimmediately following the outlets of cylinders storing hydrogen gas andfluorine gas.

As shown in FIG. 8, while the flow rate of the F₂/N₂ gas introduced intothe processing chamber 11 through the fluorine/nitrogen supply pipe 42is kept constant, the H₂/N₂ gas is intermittently supplied. Thus, thestep of supplying both hydrogen gas, which is a combustible gas, andfluorine gas, which is a combustion-supporting gas, into the processingchamber 11, and the step of supplying only fluorine gas, which is acombustion-supporting gas, are alternately performed. For instance,while continuously supplying the F₂/N₂ gas, the cycle of supplying theH₂/N₂ gas for 10 seconds and stopping it for 20 seconds is repeated.

According to this embodiment, when the F₂/N₂ gas and the H₂/N₂ gas areboth supplied into the processing chamber 11, the reaction of fluorinegas (F₂) and hydrogen gas (H₂) occurs in the processing chamber 11,generating hydrogen fluoride gas (HF) and producing heat of reaction.Thus, the deposition film adhered to the processing chamber 11, thewafer boat 12 and the like is etched by the generated hydrogen fluoridegas (HF) and fluorine gas (F₂), and simultaneously the processingchamber 11, the wafer boat 12 and the like are heated by the heat ofreaction.

When the supply of the H₂/N₂ gas is stopped and only the F₂/N₂ gas issupplied into the processing chamber 11, the reaction of fluorine gas(F₂) and hydrogen gas (H₂) scarcely occurs, and etching proceeds by thealready generated hydrogen fluoride gas and fluorine gas. At this time,because no heat of reaction is produced, the processing chamber 11, thewafer boat 12 and the like are cooled.

Thus, according to this embodiment, the processing chamber 11, the waferboat 12 and the like are heated and cooled. Hence, their temperaturedoes not significantly increase. In contrast, even if the total supplyamount of hydrogen gas is the same, continuously supplying it at aconstant flow rate causes heat of reaction to be continuously producedin the same region inside the processing chamber 11, and the sameportion of the processing chamber 11, the wafer boat 12 and the like iscontinuously heated. Hence, this portion eventually reaches aconsiderably high temperature and is damaged. In other words, in thisembodiment, a large flame is intermittently produced by the reaction ofhydrogen gas and fluorine gas. Hence, as compared with the case ofcontinuously producing a small flame, local heating can be prevented.Thus, this embodiment can also prevent damage to the processing chamber11, the wafer boat 12 and the like due to cleaning.

Furthermore, in this embodiment, nitrogen gas is supplied as a coolingand dilution gas into the processing chamber 11 in addition to hydrogengas, which is a combustible gas, and fluorine gas, which is acombustion-supporting gas. Thus, the deposition film can be etched whilethe atmosphere in the processing chamber 11 is cooled. This also servesto prevent damage due to heat of reaction. Furthermore, local etchingcan be prevented also by diluting hydrogen gas and fluorine gas withnitrogen gas. Moreover, the mixing effect can be enhanced by mixinghydrogen gas and fluorine gas with nitrogen gas at a position far fromthe processing chamber 11.

Next, a fourth embodiment of the invention is described.

FIG. 9 is a graph illustrating change in the supply amount of each gasin this embodiment, where the horizontal axis represents time, and thevertical axis represents gas supply amount.

The LPCVD apparatus used in this embodiment is the same as the LPCVDapparatus 3 (see FIG. 7) used in the above third embodiment.

In the following, a method for cleaning a semiconductor manufacturingapparatus according to this embodiment is described.

As shown in FIG. 7, also in this embodiment, like the above thirdembodiment, in the LPCVD apparatus 3, a H₂/N₂ gas is introduced into theprocessing chamber 11 through the hydrogen/nitrogen supply pipe 41, anda F₂/N₂ gas is introduced into the processing chamber 11 through thefluorine/nitrogen supply pipe 42.

Here, as shown in FIG. 9, while the supply amount of hydrogen gas andfluorine gas is kept constant, the supply amount (hereinafter referredto as “first supply amount”) of nitrogen gas for diluting the hydrogengas, that is, nitrogen gas supplied through the hydrogen/nitrogen supplypipe 41, and the supply amount (hereinafter referred to as “secondsupply amount”) of nitrogen gas for diluting the fluorine gas, that is,nitrogen gas supplied through the fluorine/nitrogen supply pipe 42, areeach changed temporally.

Specifically, while the total amount of the first supply amount and thesecond supply amount is kept constant, the first supply amount and thesecond supply amount are changed complementarily. That is, the step ofrelatively increasing the first supply amount and relatively decreasingthe second supply amount, and the step of relatively decreasing thefirst supply amount and relatively increasing the second supply amount,are alternately performed.

According to this embodiment, the supply amount (first supply amount) ofN₂ gas for diluting H₂ gas and the supply amount (second supply amount)of N₂ gas for diluting F₂ gas are changed complementarily. Thistemporally changes, in the processing chamber 11, the region ofcollision and reaction between hydrogen gas and fluorine gas, and hencetemporally changes also the region where heat of reaction is produced.Consequently, the temperature distribution in the processing chamber 11is uniformized, and no portion is continuously heated. Thus, localdamage to the processing chamber 11 and the wafer boat 12 or other jigcan be prevented. That is, in this embodiment, the position of the flameis temporally moved so that intensive heating of a particular portioncan be prevented.

Furthermore, like the above third embodiment, this embodiment can alsoachieve the cooling effect by introducing nitrogen gas. Thus, thisembodiment can also prevent damage to the processing chamber 11, thewafer boat 12 and the like due to cleaning.

Furthermore, according to this embodiment, the supply amount of hydrogengas and fluorine gas is kept constant, and the total supply amount ofnitrogen gas, that is, the total amount of the first supply amount andthe second supply amount described above is also kept constant. Hence,the total amount of reaction can be kept constant. This allows stableetching.

Moreover, also in this embodiment, like the above third embodiment,hydrogen gas and fluorine gas, which are actual gases responsible forreaction, are diluted with nitrogen gas not responsible for reaction sothat local etching in the processing chamber 11 can be prevented. Here,mixing of hydrogen gas and nitrogen gas and mixing of fluorine gas andnitrogen gas are performed preferably at a position far away from theprocessing chamber 11. This can further enhance the effect of mixing.

Next, a first variation of the fourth embodiment is described.

FIG. 10 is a graph illustrating change in the supply amount of each gasin this variation, where the horizontal axis represents time, and thevertical axis represents gas supply amount.

As shown in FIG. 10, this variation is the same as the above fourthembodiment in that the supply amount (first supply amount) of nitrogengas for diluting hydrogen gas and the supply amount (second supplyamount) of nitrogen gas for diluting fluorine gas are changedcomplementarily with the total amount kept constant. However, in thisvariation, the first and second supply amounts are each allowed to takeon multiple values.

According to this variation, the position of reaction between hydrogengas and fluorine gas can be changed among three or more positions in theprocessing chamber 11. Thus, the temperature in the processing chamber11 can be uniformized more effectively. Consequently, local damage tothe processing chamber 11 and the wafer boat 12 or other jig can beprevented more effectively. The cleaning method and its effect of thisvariation other than the foregoing are the same as those of the abovefourth embodiment.

Next, a second variation of the fourth embodiment is described.

FIG. 11 is a graph illustrating change in the supply amount of each gasin this variation, where the horizontal axis represents time, and thevertical axis represents gas supply amount.

As shown in FIG. 11, this variation is also the same as the above fourthembodiment in that the first supply amount and the second supply amountare changed complementarily with the total amount thereof kept constant.However, in this variation, the first and second supply amounts are eachchanged gradually.

More specifically, from the state where the first supply amount isminimized and the second supply amount is maximized, the first supplyamount is gradually increased, and the second supply amount is graduallydecreased. Thus, the first supply amount is maximized, and the secondsupply amount is minimized. Subsequently, the first supply amount isgradually decreased, and the second supply amount is graduallyincreased. Thus, the first supply amount is minimized, and the secondsupply amount is maximized. This cycle is repeated.

In this variation, the position of reaction between hydrogen gas andfluorine gas can be gradually changed in the processing chamber 11.Thus, the temperature in the processing chamber 11 can be made moreuniform, and local damage to the processing chamber 11 and the like canbe prevented more effectively. The cleaning method and its effect ofthis variation other than the foregoing are the same as those of theabove fourth embodiment.

In the above fourth embodiment and the first and second variationthereof, the total amount of the first supply amount and the secondsupply amount is illustratively kept constant. However, the invention isnot limited thereto, but the total amount can be changed. Here, it isalso possible to change only one of the first supply amount and thesecond supply amount. Furthermore, in the above fourth embodiment andthe first and second variation thereof, the first and second supplyamounts are illustratively changed stepwise. However, the first andsecond supply amount can also be changed continuously.

Next, a fifth embodiment of the invention is described.

FIG. 12 is a plan view illustrating a semiconductor manufacturingapparatus according to this embodiment.

FIG. 13 is a graph illustrating a cleaning method according to thisembodiment, where the horizontal axis represents time, and the verticalaxis represents gas supply amount.

The semiconductor manufacturing apparatus according to this embodimentis also an LPCVD apparatus.

As shown in FIG. 12, in contrast to the LPCVD apparatus 3 (see FIG. 7)in the above third embodiment, the LPCVD apparatus 5 according to thisembodiment includes a plurality of hydrogen/nitrogen supply pipes forintroducing a mixed gas (H₂/N₂ gas) of hydrogen gas (H₂) and nitrogengas (N₂) into the processing chamber 11, which are coupled to differentpositions of the processing chamber 11. For instance, the example shownin FIG. 12 includes three hydrogen/nitrogen supply pipes 41 a, 41 b, and41 c, which are arranged in this order from the fluorine/nitrogen supplypipe 42 side on the same horizontal plane. In FIG. 12, for convenienceof illustration, the components other than the processing chamber 11,the hydrogen/nitrogen supply pipes 41 a, 41 b, and 41 c, and thefluorine/nitrogen supply pipe 42 are not shown.

Next, a description is given of the operation of the LPCVD apparatusaccording to this embodiment configured as described above, that is, amethod for cleaning a semiconductor manufacturing apparatus according tothis embodiment.

As shown in FIGS. 12 and 13, in this embodiment, the supply pipe forpassing the H₂/N₂ gas is temporally changed among the threehydrogen/nitrogen supply pipes 41 a, 41 b, and 41 c. For instance, theH₂/N₂ gas is first supplied through the hydrogen/nitrogen supply pipe 41a into the processing chamber 11. Next, the H₂/N₂ gas is suppliedthrough the hydrogen/nitrogen supply pipe 41 b. Next, the H₂/N₂ gas issupplied through the hydrogen/nitrogen supply pipe 41 c. Subsequently,this cycle is repeated. On the other hand, the F₂/N₂ gas is suppliedinto the processing chamber 11 through the same fluorine/nitrogen supplypipe 42.

Thus, by temporally switching the hydrogen/nitrogen supply pipe forpassing the H₂/N₂ gas, the position where the H₂/N₂ gas and the F₂/N₂gas collide and hydrogen gas and fluorine gas react is temporallychanged in the processing chamber 11. For instance, in the example shownin FIG. 12, hydrogen gas and fluorine gas react primarily in region Rawhen the hydrogen/nitrogen supply pipe 41 a is in use, react primarilyin region Rb when the hydrogen/nitrogen supply pipe 41 b is in use, andreact primarily in region Rc when the hydrogen/nitrogen supply pipe 41 cis in use. Thus, the position of the flame, so to speak, is temporallymoved, and hence the temperature distribution in the processing chamber11 is uniformized. This avoids intensive heating of a particular portionin the processing chamber 11 and the wafer boat 12 or other jig, andlocal damage can be prevented. Thus, this embodiment can also preventdamage to the processing chamber 11, the wafer boat 12 and the like dueto cleaning.

Furthermore, also in this embodiment, like the above third and fourthembodiment, hydrogen gas and fluorine gas are diluted with nitrogen gasso that local etching in the processing chamber 11 can be prevented.Here, mixing of gases is performed preferably at a position distancedfrom the processing chamber 11. This can further enhance the effect ofmixing.

In this embodiment, only one fluorine/nitrogen supply pipe 42 and aplurality of hydrogen/nitrogen supply pipes are provided, for instance.However, the invention is not limited thereto. For instance, it is alsopossible to provide only one hydrogen/nitrogen supply pipe and aplurality of fluorine/nitrogen supply pipes. Alternatively, both thehydrogen/nitrogen supply pipe and the fluorine/nitrogen supply pipe canbe provided in a plurality.

In this embodiment, the plurality of hydrogen/nitrogen supply pipes areillustratively used one by one. However, the invention is not limitedthereto. A plurality of hydrogen/nitrogen supply pipes can be used incombination at an arbitrary timing. For instance, it is possible to usethe hydrogen/nitrogen supply pipe 41 a in a first period, thehydrogen/nitrogen supply pipe 41 b in a second period, thehydrogen/nitrogen supply pipe 41 c in a third period, thehydrogen/nitrogen supply pipes 41 a and 41 b in a fourth period, thehydrogen/nitrogen supply pipes 41 b and 41 c in a fifth period, thehydrogen/nitrogen supply pipes 41 c and 41 a in a sixth period, and thehydrogen/nitrogen supply pipes 41 a, 41 b, and 41 c in a seventh period.Thus, the position of reaction in the processing chamber 11 can bechanged in a more complex manner, and the temperature distribution inthe processing chamber 11 can be uniformized more effectively.

Furthermore, in this embodiment, a mixed gas (H₂/N₂ gas) of hydrogen gasand nitrogen gas and a mixed gas (F₂/N₂ gas) of fluorine gas andnitrogen gas are illustratively supplied into the processing chamber 11.However, nitrogen gas can be replaced by other dilution gases which donot react with hydrogen gas and fluorine gas, or it is also possible touse no dilution gas.

The invention has been described with reference to the embodiments.However, the invention is not limited to these embodiments. Forinstance, the above embodiments can be practiced in combination witheach other. For instance, also in the above first embodiment, nitrogengas can be introduced as a cooling gas like the above second embodiment.Furthermore, those skilled in the art can suitably modify the aboveembodiments by addition, deletion, or design change of components, or byaddition, omission, or condition change of processes, and suchmodifications are also encompassed within the scope of the invention aslong as they fall within the spirit of the invention.

For instance, in the above embodiments, the semiconductor manufacturingapparatus is illustratively an LPCVD apparatus. However, the inventionis not limited thereto, but applicable to any semiconductormanufacturing apparatus for manufacturing a semiconductor device inwhich a deposition film is formed in the course of its use. Forinstance, the invention is applicable to various film formationapparatuses, etching apparatuses, and other processing apparatuses. Inthis case, the processing chamber is an apparatus in which a siliconwafer or other workpiece is received and subjected to certain processessuch as film formation and processing with the atmosphere therein beingcontrolled.

The above embodiments illustratively use hydrogen gas (H₂) as acombustible gas and fluorine gas (F₂) as a combustion-supporting gas.However, the invention is not limited thereto. Any two or more gasesgenerating a cleaning gas by an exothermic reaction can be used as acombustible gas and a combustion-supporting gas. Furthermore, in theabove embodiments, the cooling mechanism is illustratively awater-cooling apparatus or a cooling gas, such as nitrogen gas (N₂).However, the invention is not limited thereto, but other coolingmechanism can also be used. For instance, the reaction chamber 13 in thefirst embodiment can be forced-air cooled.

1. A semiconductor manufacturing apparatus comprising: a processingchamber; and a reaction cooling apparatus placed outside the processingchamber and configured to generate a cleaning gas by reaction of acombustible gas and a combustion-supporting gas and to cool the cleaninggas, the cleaning gas which is cooled being supplied into the processingchamber.
 2. The apparatus according to claim 1, wherein the reactioncooling apparatus includes: a reaction chamber supplied with thecombustible gas and the combustion-supporting gas and configured tocause the reaction; and a water-cooling apparatus configured to cool thecleaning gas.
 3. The apparatus according to claim 1, wherein thereaction cooling apparatus is configured to mix the combustible gas, thecombustion-supporting gas, and a cooling gas.
 4. The apparatus accordingto claim 3, wherein the reaction cooling apparatus includes: an outertube in connection with the processing chamber; a middle tube placed inthe outer tube and terminated at a position spaced from the processingchamber, the termination being opened to inside the outer tube; and aninner tube placed in the middle tube and terminated at a position spacedfrom the processing chamber, the termination being opened to inside theouter tube, one of the combustible gas and the combustion-supporting gasis supplied into the inner tube, and the other is supplied between theinner tube and the middle tube, and the cooling gas is supplied betweenthe middle tube and the outer tube.
 5. The apparatus according to claim1, wherein the reaction cooling apparatus includes a heater configuredto heat the cleaning gas.
 6. The apparatus according to claim 1, whereinthe combustible gas is hydrogen gas, and the combustion-supporting gasis fluorine gas.
 7. The apparatus according to claim 1, wherein thesemiconductor manufacturing apparatus is a CVD apparatus.
 8. Asemiconductor manufacturing apparatus comprising: a processing chamber;a combustible gas supply pipe configured to supply a combustible gasinto the processing chamber; a combustion-supporting gas supply pipeconfigured to supply a combustion-supporting gas into the processingchamber; and at least one of another combustible gas supply pipe andanother combustion-supporting gas supply pipe, one of the combustiblegas supply pipe and the another combustible gas supply pipe for passingthe combustible gas is temporally changed among them or one of thecombustion-supporting gas supply pipe and the anothercombustion-supporting gas supply pipe for passing thecombustion-supporting gas is temporally changed among them.
 9. Theapparatus according to claim 8, wherein the combustible gas is hydrogengas, and the combustion-supporting gas is fluorine gas.
 10. Theapparatus according to claim 8, wherein the semiconductor manufacturingapparatus is a CVD apparatus.
 11. A method for cleaning a semiconductormanufacturing apparatus, comprising: a first supplying a combustible gasand a combustion-supporting gas into a processing chamber; and a secondsupplying the combustion-supporting gas into the processing chamber, thefirst supplying and the second supplying being alternately performed.12. The method according to claim 11, wherein hydrogen gas is used asthe combustible gas, and fluorine gas is used as thecombustion-supporting gas.
 13. A method for cleaning a semiconductormanufacturing apparatus, comprising: supplying a combustible gas and adilution gas into a processing chamber through a combustible gas supplypipe, and simultaneously supplying a combustion-supporting gas and adilution gas into the processing chamber through a combustion-supportinggas supply pipe, at least one of a first supply amount of the dilutiongas supplied through the combustible gas supply pipe and a second supplyamount of the dilution gas supplied through the combustion-supportinggas supply pipe being temporally changed.
 14. The method according toclaim 13, wherein total amount of the first supply amount and the secondsupply amount is kept constant.
 15. The method according to claim 13,wherein the supplying the combustible gas and the dilution gas and thesimultaneously supplying the combustion-supporting gas and the dilutiongas includes: a first supplying; and a second supplying, the firstsupply amount of the first supplying is more than the first supplyamount of the second supplying, the second supply amount of the secondsupplying is more than the second supply amount of the first supplying,and the first supplying and the second supplying are alternatelyperformed.
 16. The method according to claim 13, wherein the firstsupply amount and the second supply amount have each multiple values.17. The method according to claim 13, wherein the first supply amountand the second supply amount are each changed gradually.
 18. The methodaccording to claim 13, wherein hydrogen gas is used as the combustiblegas, and fluorine gas is used as the combustion-supporting gas.
 19. Themethod according to claim 13, wherein nitrogen gas is used as thedilution gas.
 20. A method for cleaning a semiconductor manufacturingapparatus including a processing chamber, a combustible gas supply pipeconfigured to supply a combustible gas into the processing chamber, anda combustion-supporting gas supply pipe configured to supply acombustion-supporting gas into the processing chamber, at least one ofthe combustible gas supply pipe and the combustion-supporting gas supplypipe being provided in a plurality, the method comprising: temporallychanging the supply pipe for passing the combustible gas or thecombustion-supporting gas among the plurality of combustible gas supplypipes or the plurality of combustion-supporting gas supply pipes.